Autoimmune liver diseases (AILDs), including autoimmune hepatitis (AIH), primary biliary cirrhosis (PBC), and primary sclerosing cholangitis (PSC), are chronic and incurable immune disorders of the liver. AILDs result in marked suffering and serious consequences of AILDs lead to liver failure and hepatobiliary malignancy. Clinical problems and challenges: Diagnosis of specific AILD subtypes has been clinically challenging, due to significant clinical heterogeneity and the overlap syndrome where AIH coexists with PBC/PSC, and AILDs overlap with inflammatory bowel disease (IBD). Another major challenge is the lack of reliable biomarkers for evaluating disease progression and treatment response, particularly in PSC. Disease diagnosis/prognosis relies heavily on clinical presentations as well as invasive and resource-consuming biopsy-based histopathology. Thus, the long-term objective of this study is to identify and develop reliable, less invasive, and less expensive serum biomarkers to assist physicians to make accurate diagnosis/prognosis and treatment decisions, leading to effective management of AILDs and improved patients' quality of life. Rationale and hypothesis: Blood-based biomarker testing is generally the simplest, least invasive, and most widely used for disease diagnosis/prognosis. Most of the current AILD biomarkers are autoantibodies, such as ANA/SMA for type-1 AIH; AMA for PBC (no specific PSC marker), suggesting that serum autoantibodies are important sources for AILD biomarkers. Cytokines/chemokines, known to play essential roles in the pathogenesis of AILDs, are another potential source of AILD biomarkers. However, extensive screening aimed to identify disease-specific autoantibodies and cytokines as serum AILD biomarkers has been difficult due to the lack of high throughput technologies. Recently, through high-throughput profiling of serum cytokines (by multiplex ELISA) and autoantibodies (by human protein chip technology), we have preliminary data demonstrating that highly discriminate profiles of serum cytokines and autoantibodies are present and identifiable in AIH vs PBC vs PSC. Specific aims: We propose to combine the state-of-art high-throughput multiplex ELISA and protein chip technologies with advanced bioinformatic analysis, to identify unique profiles of serum cytokines and autoantibodies as novel non-invasive biomarkers for 1) better diagnosis of AIH, PBC and PSC, and 2) differentiating two PSC subtypes: PSC only vs PSC that overlaps with IBD. Significance: The success of this project could lead to development of new, reliable and non-invasive biomarkers for accurate and early/timely diagnosis/prognosis, and thus enabling more timely and effective therapeutic intervention, and prevent or delay the irreversible late/end-stage of the diseases such as liver failure. Moreover, identifying disease-specific cytokines and autoantibodies in AILDs, may not only provide new mechanistic insights into the disease pathogenesis, but also potentially lead to the identification of novel molecular targets for future development of new AILD therapeutics.